你可以试试这个:

SELECT code1, code2
FROM myTable
WHERE code1 IN 
    (SELECT code1 FROM myTable GROUP BY code1 HAVING COUNT(code1) > 1)

或者像这样使用 INNER JOIN :

SELECT t.code1, code2
FROM myTable t
  INNER JOIN
    (SELECT code1 FROM myTable GROUP BY code1 HAVING COUNT(code1) > 1)
     s on s.code1 = t.code1